The present invention relates to marine transportation combinations and more specifically to intergrated push-towing combinations for use in open seas.
The use of marine push-towing combinations such as tugs and barges is widely accepted as an efficient, economical means of transporting cargo from one location to another. The utilization of separate vessels, one furnishing power, the other carrying cargo, allows more efficient use of the powered vessel inasmuch as when the cargo vessel has been moved to the desired destination, the powered vessel need not remain idle while the cargo is being unloaded. Thus for example, the powered vessel can be used to transport another cargo vessel to some other destination. Such an arrangement also leads to more efficient use of the crew of the powered craft. In typical powered, ocean going cargo ships, when the ship reaches its destination, the crew of the ship is relatively idle while the cargo is being unloaded by longshoremen. This of course increases the cost of shipping which is already rising at a very rapid rate due to the increased cost of construction of ships and the maintenance thereof.
Thus, while articulated vessels, i.e., ships consisting of several units as for example a cargo vessel separate from a power vessel, possess distinct advantages, their use has been limited to inland waterways such as rivers, lakes and protected bays. Such articulated vessels have not been satisfactory for ocean going shipments due primarily to the action of winds, waves, and tides which are encountered in such environments. Several articulated combinations have been proposed for open water use such as those shown in U.S. Pat. Nos. 3,362,372 and 3,486,476. These prior art systems and other similar ones suffer from the disadvantage that engagement and disengagement of the powered vessel and the cargo vessel cannot be accomplished as rapidly as is necessary in the event the powered vessel needs to unmate from the cargo vessel for safety reasons. Moreover, most of the prior art marine combinations proposed for such use have not provided a means whereby the coupling between the powered and the cargo vessel is rigid such that the two craft will act as a unitary vessel when they are mated.